Atomic Structures
&
Properties

Observations:
- Most alpha particles passed
through foil
-A few alpha particles were
deflected at large angles

Inferences:
- Atoms are mostly empty space
- The existence of a positively charged
nucleus

Contributions
- Introduced the nuclear
model with a central nucleus
- Suggested that electrons orbit
the nucleus

Electron Groups: 3

Bonded Atoms: 2

Lone Pairs: 1

Bond Angles: <120°

Example: SO2

Electron Groups: 3

Bonded Atoms: 3

Lone Pairs: 0

Bond Angles: 120°

Example: BF3

Electron Groups: 4

Bonded Atoms: 3

Lone Pairs: 1

Bond Angles: <109.5°

Example: NH3

Electron Groups: 5

Bonded Atoms: 3

Lone Pairs: 2

Bond Angles: <90°

Example: ClF3

Electron Groups: 6

Bonded Atoms: 4

Lone Pairs: 2

Bond Angles: 90°

Example: XeF4

The physical properties of solids and liquids depend on intermolecular forces (dispersion, dipole-dipole, hydrogen bonding, ion-dipole) and intramolecular forces (covalent, ionic, metallic). Stronger forces lead to higher melting and boiling points. Covalent network solids are very hard, ionic compounds are hard and brittle, and metals are malleable and conductive. Solubility follows "like dissolves like."

Observations:
- emission spectra of
hydrogen show discrete
lines

Inferences:
- Electrons Orbit the nucleus
- Electrons emit or absorb energy

Contributions
- Introduced quantized
electron orbits
- Explained stability of electron
orbits and spectral lines

Electron Groups: 2

Bonded Atoms: 2

Lone Pairs: 0

Bond Angles: 180°

Example: CO2

Electron Groups: 4

Bonded Atoms: 4

Lone Pairs: 0

Bond Angles: 109.5°

Example: CH4

Electron Groups: 5

Bonded Atoms: 5

Lone Pairs: 0

Bond Angles: 90°, 120°

Example: PCl5

Electron Groups: 6

Bonded Atoms: 6

Lone Pairs: 0

Bond Angles: 90°

Example: SF6

Electron Groups: 5

Bonded Atoms: 4

Lone Pairs: 1

Bond Angles: <90°, <120°

Example: SF4

Electron Groups: 6

Bonded Atoms: 5

Lone Pairs: 1

Bond Angles: <90°

Example: BrF5